[infinispan-dev] trace vs log.isTraceEnabled

[Dan Berindei]

Manik, I believe the constants are interned the moment the class is loaded,
so there's no extra work to pass int to the trace method.
 În data de 07.12.2011 12:43, "Manik Surtani" <manik at jboss.org> a scris:

> Bringing this thread up again, is it really true to say that
>
>   if (trace) log.trace("blah")
>
> is as cheap as
>
>  log.trace("blah")
>
> ?
>
> In the former, with tracing disabled, nothing happens after the condition
> check.  In the latter, you still construct a String "blah", and even if
> there is no complex interpolation or message construction, the basic String
> message is still constructed (and starts to take up PermGen space too, as
> literals are interned [1]).
>
> So the case for the if (trace) pattern still stands IMO.
>
> Cheers
> Manik
>
> [1]
> http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/String.html#intern()
> "All literal strings and string-valued constant expressions are interned."
>
> On 28 Sep 2011, at 17:41, David M. Lloyd wrote:
>
> > On 09/28/2011 11:35 AM, Mircea Markus wrote:
> >> Hi,
> >>
> >> I'm not aware of any convention on using trace vs log.isTraceEnabled()
> to guard the trace statements.
> >>
> >> if (trace) log.trace("some request related stuff")
> >> vs
> >> if (log.isTraceEnabled()) log.trace("some request related stuff");
> >>
> >> The former is more efficient, but cannot be managed at runtime. It
> seems to be the preferred form, so shall we stick with it?
> >
> > If you're using the jboss-logging API, and your log statement does not
> > do any interpolation, then it is just as fast to do any of the following
> > (with no if):
> >
> >    log.trace("blah");
> >    log.tracef("the %s happened to %s", foo, bar);
> >    log.tracev("the {0} happened to {1}", foo, bar);
> >
> > In the case where trace logging is disabled, these are exactly as
> > efficient as the if (log.isTraceEnabled()) variants.  In the case where
> > it is enabled, it is marginally more efficient (though the trace log
> > itself is substantially more expensive of course).
> >
> > Overall I'd avoid the "if" forms unless you're doing complex
> interpolation:
> >
> >    log.trace("Foo " + bar + " baz " + zap);
> >    log.tracef("the %s happened to %s", fooMethod().barMethod(), bar);
> >
> > ...both of which incur the expense of the expression resolution even if
> > the log message is ultimately discarded.
> > --
> > - DML
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> > infinispan-dev at lists.jboss.org
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>
> --
> Manik Surtani
> manik at jboss.org
> twitter.com/maniksurtani
>
> Lead, Infinispan
> http://www.infinispan.org
>
>
>
>
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